Doing some calculations I get:
Brunhilde's base craft weaponsmithing is: 1 rank + 2 ability + 3 trained + 2 craftswoman = +8
That plus Greg's assisting giving a +2 is +10 total
Greatsword = 50gp = 500sp @ DC15, going to accelerated craft gives DC25
Taking 20, Brun aided makes progress of CHECK30 * DC25 = 750sp per week, so the basic halfling sized Greatsword is ready in little less than 5 days.
The MWK part (which is calculated separately) is 300gp = 3000sp @ DC20, going to accelerated craft gives DC30
Taking 20 Brun aided makes progress of CHECK30 * DC30 = 900sp per week, so making the greatsword MWK takes Brunhilde 3 1/3 weeks of work. Four weeks total, not bad for having only one rank
. Also she gets a 5% additional cost reduction for working on metal parts.